System for treating unwanted tissue

ABSTRACT

The invention may be applied to selectively heat a diseased area in the lung while minimizing heating to the healthy area and surrounding tissue. This can be done by exposing the lung to an electromagnetic field causing dielectric or eddy current heating. The invention is particularly useful for treating emphysema as the diseased areas in emphysema patients have reduced blood flow. The diseased area will heat up rapidly while the healthy tissue will be cooled by the blood flow. This is particularly effective for treating emphysema because of the low mass of the lungs and the high blood flow. To avoid heating of surrounding organs the direction of the electromagnetic energy may be switched in a way it always passes through lungs but only intermittently passes through adjacent organs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Application No. 62/341,229filed 25 May 2016 and U.S. Application No. 62/468,869 filed 8 Mar. 2017.For purposes of the United States, this application claims the benefitunder 35 U.S.C. § 119 of U.S. Application No. 62/341,229 filed 25 May2016 entitled CLOSED LOOP CONTROL OF TREATMENT FOR EMPHYSEMA and U.S.Application No. 62/468,869 filed 8 Mar. 2017 entitled SYSTEM FORTREATING UNWANTED TISSUE, each one of which is hereby incorporatedherein by reference for all purposes.

FIELD

The invention relates to the medical field and in particular to thetreatment of unwanted tissues. The invention has example application intreating lung diseases such as chronic obstructive pulmonary disease(COPD), one example of which is emphysema.

BACKGROUND

There are a variety of medical conditions for which treatment canbeneficially include destroying or affecting a non-desired tissue. Suchtreatments should ideally avoid harming normal tissues adjacent to thenon-desired tissue. For example, some lung conditions can benefit fromtreatments that involve destroying or affecting diseased lung tissue.Some of these treatments involve heating the lung tissue.

Background information on lung disease can be found in medicaltextbooks, such as “Pulmonary Pathophysiology” by Dr. John B. West, ISBN0-683-08934-X. Emphysema is a disease that damages the alevioli (airsacs) in a patient's lungs. Affected air sacs can rupture. This altersthe distribution of air spaces in the lungs and reduces the surface areaof the lungs available to take up oxygen. The lung damage caused byemphysema can trap stale air in the lungs and reduce the flow of fresh,oxygen-rich air into the lungs. In a patient suffering from emphysema,diseased parts of the patient's lungs cannot easily ventilate throughthe bronchi and trachea, thus preventing the lungs from fully deflatingand inflating. Air trapped inside the lungs can prevent the diaphragmfrom moving up and down naturally.

Some prior art approaches to heating diseased tissue within the lunginvolve inserting an ablation device through the trachea and bronchiinto the diseased area (for example, see Brannan et al. US2016/0184013). This approach has various shortcomings: only a small partof the lung is accessible, precise mapping of the diseased area isrequired, and the ablation device must be accurately guided to a preciselocation. It would be beneficial to provide a system that canautomatically heat tissues in diseased areas without having to locatethe diseased areas precisely. It would also be beneficial to be able toheat all diseased parts of the lung without excessively heating thehealthy parts or the surrounding tissue.

Armitage, U.S. Pat. No. 4,269,199 discloses a method for inducing localhyperthermia in treatment of a tumor by short wave diathermy. The methodinvolves moving an induction coil over the portion of the bodycontaining the tumor such that the axis of the coil constantly transectsdifferent portions of the tumor.

Turner, U.S. Pat. No. 4,798,215 discloses a combined hyperthermiatreatment and non-invasive thermometry apparatus.

Leveen, U.S. Pat. No. 5,010,897 discloses an apparatus for the deepheating of cancers. The apparatus employs two single turn coaxial coilswhich rotate synchronously in planes which are parallel to each otherwith the central axis of each coil lying in exactly the same line whichis perpendicular to the plane of the coil. The summated magnetic fieldof the rotating coils continuously heats a tumor.

Evans, U.S. Pat. No. 5,503,150 discloses an apparatus and method fornoninvasively locating and heating a volume of tissue that include theability to detect temperature changes in the volume of tissue.

Kasevich, U.S. Pat. No. 6,181,970 discloses medical systems andinstruments which utilize microwave energy to provide heat treatment anddiagnostic imaging of tissue.

Barry et al., U.S. Pat. No. 8,585,645 discloses treating locations in apatient's lung using high temperature vapor delivered through the innerlumen of a catheter.

Turnquist et al., US2011/0054431 discloses devices and methods tonon-invasively heat bodily tissues and fluid using emitted energy andnon-invasively measure the resulting temperature changes in the targetand surrounding fluid and tissue to detect and/or treat for variousphysical conditions, such as, for example, vesicoureteral reflux.

Lichtenstein et al., U.S. Pat. No. 8,444,635 which is herebyincorporated herein by reference discloses a system that exposesundesired tissue to a scanning focused microwave beam. U.S. Pat. No.8,444,635 explains that the system is particularly useful for heatingtissues in which the undesired tissue has reduced blood flow. Theundesired tissues will heat up relatively rapidly while surroundinghealthy tissues will be cooled by the blood flow. This differentialheating effect is particularly strong in the lungs because healthy lungtissue has low density and high blood flow. U.S. Pat. No. 8,444,635provides as an example application treating emphysema.

Vertikov et al., U.S. Pat. No. 8,467,858 describes devices andtechniques for thermotherapy based on optical imaging.

There remains a need for apparatus and methods useful for controllingand/or delivering hyperthermy treatments.

SUMMARY

This invention has a number of aspects. These aspects include, withoutlimitation:

-   -   Apparatus useful for selectively heating tissues within a        patient;    -   Control systems for hyperthermy apparatus;    -   Methods for controlling apparatus for selectively heating        tissues within a patient;    -   Methods for treating a patient which include selective heating        of tissues within the patient.        An example and non-limiting application of methods and apparatus        as described herein is treatment of diseased lung tissues, for        example, lung tissues affected by emphysema or other forms of        COPD.

Innovations described herein include:

-   -   Apparatus and methods useful in providing closed-loop control of        temperature in tissues of a patient;    -   Apparatus and methods useful for planning delivery of        electromagnetic radiation to heat target tissues in a patient;    -   Apparatus and methods useful for heating tissues in patients        with compensation and/or accommodation for differential        perfusion;    -   Apparatus and methods useful for heating tissues in patients        which include novel feature combinations;    -   Medical methods for treatment of emphysema and/or COPD.        These innovations may be applied individually or in any        combinations.

Further aspects and example embodiments are illustrated in theaccompanying drawings and/or described in the following description.

Enumerated Example Embodiments

The following enumerated example embodiments illustrate variousnon-limiting aspects of the invention.

1. Medical thermal ablation apparatus useful for treatment of emphysemaor COPD, the apparatus comprising:

-   -   a plurality of electromagnetic signal applicators, the plurality        of electromagnetic signal applicators adapted to deliver        electromagnetic energy to lung tissues for differential heating        of diseased and healthier portions of the lung tissues, the        plurality of electromagnetic signal applicators comprising a        first set of two or more first electromagnetic signal        applicators positionable on one side of a body to be treated and        at a second set of at least one second electromagnetic signal        applicators positionable on a second side of the body to be        treated opposed to the first side such that the body is between        the first and second electromagnetic signal applicators (or any        other aspect herein) wherein the first and second        electromagnetic signal applicators;    -   a heating energy signal generator;

a selector circuit connected to receive an output signal from theheating energy signal generator and to selectively apply the outputsignal between any of a plurality of pairs of the electromagnetic signalapplicators, the pairs of the electromagnetic signal applicators eachcomprising one of the first electromagnetic signal applicators and oneof the second electromagnetic signal applicators;

a controller connected to control the selector circuit, the controlleroperable to switch from applying the output signal from a currentlyselected one of the pairs of electromagnetic signal applicators to adifferent one of the pairs of electromagnetic signal applicators atspaced apart times.

2. The medical thermal ablation apparatus according to aspect 1 (or anyother aspect herein) (or any other aspect herein) wherein theelectromagnetic signal applicators each comprises an electrode.

3. The medical thermal ablation apparatus according to aspect 2 (or anyother aspect herein) comprising an impedance matching network betweenthe heating energy signal generator and the electrodes.

4. The medical thermal ablation apparatus according to aspect 3 (or anyother aspect herein) wherein the impedance matching network comprises aplurality of settings, each of the settings provides impedance matchingfor at least one of the plurality of pairs of electrodes, each of thepairs of electrodes correspond to one of the settings and the controlleris connected to control the impedance matching network to switch theimpedance matching network to the setting corresponding to the currentlyselected one of the pairs of electrodes.5. The medical thermal ablation apparatus according to any one ofaspects 2 to 4 (or any other aspect herein) wherein the controller isconfigured to switch from applying the output signal from the currentlyselected one of the pairs of electrodes to a different one of the pairsof electrodes at a frequency of 100 Hz or less.6. The medical thermal ablation apparatus according to any one ofaspects 2 to 5 (or any other aspect herein) wherein the electrodeselector circuit comprises a first switch or network of switchesswitchable to connect a first output of the heat energy signal generatorto one of the first electrodes.7. The medical thermal ablation apparatus according to any one ofaspects 2 to 6 (or any other aspect herein) wherein the secondelectrodes comprise a plurality of second electrodes and the electrodeselector circuit comprises a second switch or network of switchesswitchable to connect a second output of the heat energy signalgenerator to one of the plurality of second electrodes.8. The medical thermal ablation apparatus according to aspect 7 (or anyother aspect herein) wherein one of the first and second outputs of theheat energy signal generator is a ground potential.9. The medical thermal ablation apparatus according to any one ofaspects 1 to 8 (or any other aspect herein) wherein the heating energysignal generator comprises a radiofrequency (RF) signal generator.10. The medical thermal ablation apparatus according to aspect 9 (or anyother aspect herein) wherein the RF signal generator is operable tooutput a signal having a frequency of at least 1 MHz.11. The medical thermal ablation apparatus according to aspect 10 (orany other aspect herein) wherein the frequency is in the range of about10 MHz to about 100 MHz.12. The medical thermal ablation apparatus according to any one ofaspects 1 to 11 (or any other aspect herein) (or any other aspectherein) wherein the controller is connected to receive a temperaturesignal indicative of a temperature of tissue at one or more locationswithin the body and is configured to apply feedback control to regulateheating energy delivered into the body from the heat energy signalgenerator based at least in part on the temperature signal.13. The medical thermal ablation apparatus according to any one ofaspects 1 to 12 (or any other aspect herein) (or any other aspectherein) wherein the controller is configured to apply time domainmodulation to the output signal of the heat energy signal generator.14. The medical thermal ablation apparatus according to any one ofaspects 1 to 13 (or any other aspect herein) (or any other aspectherein) wherein the controller is configured to control the heat energysignal generator to emit the output signal as a pulsed signal and thecontroller is configured to control widths of the pulses.15. The medical thermal ablation apparatus according to any one ofaspects 12 to 14 (or any other aspect herein) further comprising asubcutaneous and/or invasive temperature sensor and the temperaturesignal comprises an output signal from the subcutaneous and/or invasivetemperature sensor.16. The medical thermal ablation apparatus according to aspect 15 (orany other aspect herein) wherein the subcutaneous and/or invasivetemperature sensor comprises a thermistor.17. The medical thermal ablation apparatus according to any one ofaspects 12 to 16 (or any other aspect herein) wherein the controllercomprises a thermal model of at least a portion of the body, the thermalmodel correlating temperature at one of the locations to temperature ofa location of interest and the controller is configured to apply thethermal model using the temperature signal as an input and to regulatethe heating energy based at least in part on an output of the thermalmodel.18. The medical thermal ablation apparatus according to aspect 17 (orany other aspect herein) wherein the thermal model models comprise someor all of: thermal conductivities of different tissue types in the body,distributions of the different tissue types in the body, geometries ofthe electromagnetic energy applicators, and blood circulation in thebody.19. The medical thermal ablation apparatus according to any one ofaspects 12 to 18 (or any other aspect herein) wherein the temperaturesignal is derived from a non-contact temperature measurement.20. The medical thermal ablation apparatus according to any one ofaspects 12 to 19 (or any other aspect herein) wherein the temperaturesignal comprises a signal derived from processing a magnetic resonanceimaging (MRI) signal.21. The medical thermal ablation apparatus according to any one ofaspects 2 to 20 (or any other aspect herein) wherein the electrodes ofat least one of the first and second sets of electromagnetic signalapplicators are arranged in an array.22. The medical thermal ablation apparatus according to aspect 21 (orany other aspect herein) wherein the array is shaped to generallyconform with a projection of a lung within the body.23. The medical thermal ablation apparatus according to aspect 21 or 22(or any other aspect herein) wherein the array is a two-dimensionalarray.24. The medical thermal ablation apparatus according to aspect 1 (or anyother aspect herein) wherein the first and second sets ofelectromagnetic signal applicators respectively comprise first andsecond two-dimensional arrays of electrodes.25. The medical thermal ablation apparatus according to aspect 24 (orany other aspect herein) wherein the two-dimensional arrays ofelectrodes are each made up of an equal number of electrodes.26. The medical thermal ablation apparatus according to aspect 24 or 25(or any other aspect herein) wherein each electrode of the first arrayof electrodes is positioned directly opposite a corresponding electrodeof the second array of electrodes.27. The medical thermal ablation apparatus according to any one ofaspects 24 to 26 (or any other aspect herein) wherein the first array ofelectrodes comprises a first column of electrodes axially spaced apartalong the body and a second column of electrodes axially spaced apartalong the body.28. The medical thermal ablation apparatus according to any one ofaspects 24 to 27 (or any other aspect herein) wherein the first andsecond arrays of electrodes have configurations that are mirror imagesof one another.29. The medical thermal ablation apparatus according to aspect 27 or 28(or any other aspect herein) wherein each of the first and secondcolumns of electrodes is made up of three to seven electrodes.30. The medical thermal ablation apparatus according to any one ofaspects 24 to 29 (or any other aspect herein) wherein the first array ofelectrodes comprises at least four columns of electrodes with theelectrodes of each column of electrodes axially spaced apart along thebody.31. The medical thermal ablation apparatus according to any one ofaspects 12 to 30 (or any other aspect herein) wherein the controller isconfigured to regulate the heating energy to raise a temperature at oneof the one or more locations to a temperature of at least 50 C and tomaintain the temperature at 50 C or higher for a selected time period.32. The medical thermal ablation apparatus according to any one ofaspects 12 to 31 (or any other aspect herein) wherein the controller isconfigured to regulate the heating energy to prevent the temperature atone of the one or more locations from exceeding a safe temperaturethreshold.33. The medical thermal ablation apparatus according to aspect 32 (orany other aspect herein) wherein the safe temperature threshold is lowerthan 50 C.34. The medical thermal ablation apparatus according to aspect 32 or 33(or any other aspect herein) wherein the controller is configured todiscontinue application of the heating energy if the temperature at theone location exceeds the safe temperature threshold.35. The medical thermal ablation apparatus according to aspect 32 or 33(or any other aspect herein) wherein the controller is configured tomodulate application of heating energy from the heating energy signalgenerator if the temperature at the one location is rising toward thesafe temperature threshold at a rate faster than a temperature risethreshold and/or is closer to the safe temperature threshold than asafety margin.36. The medical thermal ablation apparatus according to any one ofaspects 2 to 35 (or any other aspect herein) wherein the apparatuscomprises shields located between one or more of the electrodes and thebody.37. The medical thermal ablation apparatus according to aspect 36 (orany other aspect herein) wherein the shields are movable relative to theelectrodes.38. The medical thermal ablation apparatus according to aspect 36 or 37(or any other aspect herein) wherein the shields have aspatially-varying electrical impedance.39. The medical thermal ablation apparatus according to any one ofaspects 2 to 38 (or any other aspect herein) wherein the apparatuscomprises a source of an electrically conductive fluid connected tosupply the electrically conductive fluid to outlets at the electrodes.40. The medical thermal ablation apparatus according to any one ofaspects 2 to 39 (or any other aspect herein) wherein the electrodes ofthe first set of electromagnetic signal applicators are different inarea from the electrodes of the second set of electromagnetic signalapplicators.41. The medical thermal ablation apparatus according to any one ofaspects 2 to 40 (or any other aspect herein) wherein at least some ofthe electrodes comprise bladders connected to a supply of anelectrically-conductive fluid.42. The medical thermal ablation apparatus according to aspect 41 (orany other aspect herein) wherein the apparatus comprises one or morepumps connected to evacuate the electrically-conductive fluid and thecontroller is configured to operate the one or more pumps to evacuatethe electrically-conductive fluid from one or more of the bladders, whenthe electrically conductive fluid has been evacuated from the one ormore bladders operate a MRI machine to acquire MRI data from the body.43. The medical thermal ablation apparatus according to aspect 42 (orany other aspect herein) wherein the controller is configured to processthe MRI data to obtain information characterizing temperatures at one ormore locations within the body.44. The medical thermal ablation apparatus according to aspect 1 (or anyother aspect herein) wherein the electromagnetic signal applicators eachcomprises a coil.45. The medical thermal ablation apparatus according to any one ofaspects 1 to 44 (or any other aspect herein) wherein the electromagneticsignal applicators are mounted to move relative to the body.46. The medical thermal ablation apparatus according to any one ofaspects 1 to 45 (or any other aspect herein) wherein the electromagneticsignal applicators are mounted to a frame that is rotatable relative tothe body and the apparatus comprises a motor connected to drive rotationof the frame.47. The medical thermal ablation apparatus according to aspect 46 (orany other aspect herein) wherein the electromagnetic signal applicatorsare mounted for axial movement relative to the body and the apparatuscomprises one or more actuators coupled to move the electromagneticsignal applicators axially while the frame is being rotated such thatthe electromagnetic signal applicators are moved helically relative tothe body.48. The medical thermal ablation apparatus according to any one ofaspects 1 to 44 (or any other aspect herein) wherein at least one of thefirst and second electromagnetic signal applicators is stationary andthe apparatus comprises an actuator controlled by the controller andoperable to move the body relative to the at least one of the first andsecond electromagnetic signal applicators.49. The medical thermal ablation apparatus according to any one ofaspects 1 to 48 (or any other aspect herein) comprising bias means forbiasing one or more of the electromagnetic signal applicators toward thebody.50. The medical thermal ablation apparatus according to aspect 49 (orany other aspect herein) wherein the bias means comprises an inflatablechamber.51. The medical thermal ablation apparatus according to any one ofaspects 49 to 50 (or any other aspect herein) wherein the one or more ofthe electromagnetic signal applicators is flexible and the bias means isadapted to flex the one or more of the electromagnetic signalapplicators to conform to a concave surface.52. The medical thermal ablation apparatus according to aspect 50 (orany other aspect herein) comprising a source of a pressurized cool fluidin fluid communication with the inflatable chamber.53. Medical thermal ablation apparatus useful in the treatment ofemphysema or COPD, the apparatus comprising:

-   -   a heating energy signal generator;    -   one or more electromagnetic energy signal applicators connected        to receive an output signal from the heating energy signal        generator and operative to couple electromagnetic energy from        the signal generator into tissues of a body, the one or more        electromagnetic energy signal applicators comprising one or more        signal applicators selected from the group consisting of:        electrodes; coils and antennas; and    -   a controller connected to receive a connected to receive a        temperature signal indicative of a temperature of the tissue at        one or more locations within the body wherein the controller is        configured to apply feedback control to regulate heating energy        delivered into the body from the heat energy signal generator        based at least in part on the temperature signal.        54. The medical thermal ablation apparatus according to aspect        53 (or any other aspect herein) wherein the controller is        configured to apply time domain modulation to the heat energy        signal generator.        55. The medical thermal ablation apparatus according to any one        of aspects 53 to 54 (or any other aspect herein) wherein the        controller is configured to control the heat energy signal        generator to emit the output signal as a pulsed signal and the        controller is configured to control widths of pulses in the        pulsed signal.        56. The medical thermal ablation apparatus according to any one        of aspects 53 to 55 (or any other aspect herein) further        comprising a subcutaneous and/or invasive temperature sensor        wherein the temperature signal comprises an output signal from        the subcutaneous and/or invasive temperature sensor.        57. The medical thermal ablation apparatus according to aspect        56 (or any other aspect herein) wherein the subcutaneous and/or        invasive temperature sensor comprises a thermistor.        58. The medical thermal ablation apparatus according to aspect        56 or 57 (or any other aspect herein) wherein the subcutaneous        and/or invasive temperature sensor is deployed in a fine needle.        59. The medical thermal ablation apparatus according to any one        of aspects 53 to 58 (or any other aspect herein) wherein the        controller comprises a thermal model of at least a portion of        the body, the thermal model correlating temperature at one of        the locations to temperature of a location of interest and the        controller is configured to apply the thermal model using the        temperature signal as an input and to regulate the heating        energy based at least in part on an output of the thermal model.        60. The medical thermal ablation apparatus according to aspect        59 (or any other aspect herein) wherein the thermal model        comprises some or all of: thermal conductivities of different        tissue types in the body, distributions of the different tissue        types in the body, geometries of the electromagnetic energy        applicators, and blood circulation in the body.        61. The medical thermal ablation apparatus according to any one        of aspects 53 to 55 (or any other aspect herein) wherein the        temperature signal is derived from a non-contact temperature        measurement.        62. The medical thermal ablation apparatus according to aspect        61 (or any other aspect herein) wherein the temperature signal        comprises a signal derived from processing a magnetic resonance        imaging (MRI) signal.        63. The medical thermal ablation apparatus according to any one        of aspects 53 to 62 (or any other aspect herein) wherein the one        or more signal applicators are controllable to alter a direction        of electrical fields and the controller is configured to        periodically control the one or more signal applicators to alter        the direction.        64. The medical thermal ablation apparatus according to aspect        63 (or any other aspect herein) wherein the signal applicator        comprises an antenna and at least one actuator coupled to        movably position the antenna (or any other aspect herein)        wherein the controller is configured to move the antenna to        alter the direction of the electrical fields.        65. The medical thermal ablation apparatus according to aspect        63 (or any other aspect herein) wherein the signal applicator        comprises a plurality of pairs of electrodes and an electrode        selector circuit and the controller is configured to operate the        electrode selector circuit to apply an output of the heating        energy signal generator across different ones of the pairs of        electrodes at different times.        66. The medical thermal ablation apparatus according to aspect        63 (or any other aspect herein) wherein the signal applicator        comprises at least one pair of electrodes and at least one        actuator operable to move the at least one pair of electrodes        relative to a subject and the controller is connected to control        the at least one actuator.        67. The medical thermal ablation apparatus according to aspect        63 (or any other aspect herein) wherein the signal applicator        comprises a plurality of pairs of coils and a selector circuit        and the controller is configured to operate the selector circuit        to apply an output of the heating energy signal generator to the        coils of one of the pairs of coils at a time such that different        ones of the pairs of coils are carrying the output signal from        the heating energy signal generator at different times.        68. The medical thermal ablation apparatus according to aspect        63 (or any other aspect herein) wherein the signal applicator        comprises at least one pair of coils and at least one actuator        operable to move the at least one pair of coils relative to a        subject and the controller is connected to control the at least        one actuator.        69. Use of the apparatus according to any one of aspects 1 to 68        (or any other aspect herein) in the treatment of emphysema or        COPD.        70. A method for controlling a medical thermal ablation        apparatus, the apparatus useful for treatment of emphysema or        COPD, the method comprising:    -   applying a signal from a heating energy signal generator across        a pair of electromagnetic signal applicators, the        electromagnetic signal applicators adapted to deliver        electromagnetic energy to lung tissues for differential heating        of diseased and healthier portions of the lung tissues, the pair        of electromagnetic signal applicators comprising one        electromagnetic signal applicator of a first set of two or more        first electromagnetic signal applicators positionable on one        side of a body to be treated and another electromagnetic signal        applicator of a second set of at least one second        electromagnetic signal applicators positionable on a second side        of the body to be treated opposed to the first side;    -   at spaced apart times switching the signal so that the signal is        applied across a different pair of the electromagnetic signal        applicators, each different pair of the electromagnetic signal        applicators comprising one of the first electromagnetic signal        applicators and one of the second electromagnetic signal        applicators.        71. The method according to aspect 70 (or any other aspect        herein) wherein the electromagnetic signal applicators each        comprises an electrode and the method comprises matching an        impedance of the heating energy signal generator to an impedance        presented by each pair of the electromagnetic signal        applicators.        72. The method according to aspect 71 (or any other aspect        herein) comprising storing settings for an impedance matching        network in a data store and, in conjunction with switching the        signal to apply the signal across the different pair of the        electromagnetic signal applicators, configuring the impedance        matching network according to one of the settings corresponding        to the different pair of the electromagnetic signal applicators.        73. The method according to any one of aspects 70 to 72 (or any        other aspect herein) wherein the electromagnetic signal        applicators are flexible and the method comprises forming at        least one of the electromagnetic signal applicators to conform        to a concave surface.        74. The method according to aspect 73 (or any other aspect        herein) wherein forming the one of the electromagnetic signal        applicators comprises inflating a chamber adjacent to the one of        the electromagnetic signal applicators.        75. The method according to any one of aspects 70 to 74 (or any        other aspect herein) wherein switching the signal is performed        at 100 Hz or less.        76. The method according to any one of aspects 70 to 75 (or any        other aspect herein) wherein the signal comprises a        radiofrequency (RF) signal.        77. The method according to aspect 76 (or any other aspect        herein) wherein the RF signal has a frequency of at least 1 MHz.        78. The method according to aspect 76 (or any other aspect        herein) wherein the RF signal has a frequency in the range of        about 10 MHz to about 100 MHz.        79. The method according to any one of aspects 70 to 78 (or any        other aspect herein) comprising regulating an output of the        heating energy signal generator based at least in part on a        temperature signal.        80. The method according to aspect 79 (or any other aspect        herein) wherein regulating the output of the heating energy        signal generator comprises applying a feedback control        algorithm.        81. The method according to aspect 79 or 80 (or any other aspect        herein) wherein the signal comprises a pulsed signal and        regulating the output of the heating energy signal generator        comprises applying time domain modulation to the pulsed signal.        82. The method according to aspect 81 (or any other aspect        herein) wherein the time domain modulation comprises pulse width        modulation.        83. The method according to any one of aspects 70 to 82 (or any        other aspect herein) wherein the first and second sets of        electromagnetic signal applicators each comprises a two        dimensional array of electrodes.        84. The method according to aspect 83 (or any other aspect        herein) wherein the two dimensional arrays of electrodes are        shaped to conform generally to lungs of a human.        85. The method according to any one of aspects 70 to 84 (or any        other aspect herein) comprising setting a controller to regulate        the heating energy signal generator to raise a temperature at a        location to a threshold temperature and to maintain the        temperature at the threshold temperature or higher for a        selected time period.        86. The method according to aspect 85 (or any other aspect        herein) wherein the threshold temperature is at least 50° C.        87. The method according to any one of aspects 70 to 86 (or any        other aspect herein) comprising setting the controller to        regulate the heating energy signal generator to prevent the        temperature at a location from exceeding a safe temperature        threshold.        88. The method according to aspect 87 (or any other aspect        herein) wherein the safe temperature threshold is lower than 50°        C.        89. A method for treating a lung disease such as emphysema or        COPD, the method comprising:

applying electromagnetic energy to tissues of a patient's lung betweenfirst and second electromagnetic signal applicators on opposing sides ofthe patient's lung;

continuing to apply the electromagnetic energy at a power level suchthat one or more areas of diseased tissue within the lung is heated to atemperature at least equal to a treatment temperature threshold whileareas of healthier tissues of the lung are cooled by circulating bloodsuch that temperatures of the areas of healthier tissues are .maintainedbelow a safe temperature threshold that is lower than the treatmenttemperature threshold.

90. The method according to aspect 89 wherein the treatment temperaturethreshold is at least 50° C.

91. The method according to aspect 89 or 90 wherein applying theelectromagnetic energy comprises matching an impedance of a source ofthe electromagnetic energy to an impedance presented by the first andsecond electromagnetic signal applicators.

92. The method according to any one of aspects 89 to 91 comprisingchanging an orientation of the patient relative to vertical during themethod.

93. The method according to any one of aspects 89 to 92 comprisingmonitoring a temperature at a first location within the one or moreareas of diseased tissue and controlling the application of theelectromagnetic energy based on the monitored temperature of the firstlocation.94. The method according to any one of aspects 89 to 93 comprisingmonitoring a temperature at a second location within the one or moreareas of healthier tissue and controlling the application of theelectromagnetic energy based on the monitored temperature of the secondlocation.95. The method according to any one of aspects 89 to 94 comprisingforming at least one of the electromagnetic signal applicators toconform to a concave surface of the patient.96. The method according to aspect 95 wherein forming theelectromagnetic signal applicator comprises inflating an inflatablechamber adjacent to the electromagnetic signal applicator.97. The method according to any one of aspects 89 to 97 comprisingflowing a liquid between the electromagnetic signal applicators and thepatient while applying the electromagnetic energy.98. The method according to aspect 97 wherein the liquid is electricallyconductive.99. The method according to aspect 98 wherein the liquid comprises asaline solution.100. The method according to any one of aspects 89 to 99 comprisingsupplying chilled air for the patient to breathe while applying theelectromagnetic energy.101. The method according to any one of aspects 89 to 100 comprisingactively cooling one or more of the electromagnetic signal applicatorswhile applying the electromagnetic energy.102. The method according to any one of aspects 89 to 101 comprising,while applying the electromagnetic energy changing a field direction ofthe electromagnetic energy.103. The method according to aspect 102 wherein changing the fielddirection of the electromagnetic energy comprises moving the firstand/or second electromagnetic signal applicators relative to thepatient.104. The method according to aspect 103 wherein moving the first and/orsecond electromagnetic signal applicators relative to the patientcomprises moving the first and/or second electromagnetic signalapplicators along a helical path relative to the patient.105. The method according to aspect 102 wherein the firstelectromagnetic signal applicator is one of a first set of one or moreelectromagnetic signal applicators and the second electromagnetic signalapplicators is one of a second set of two or more electromagnetic signalapplicators and changing the field direction of the electromagneticenergy comprises switching to apply the electromagnetic energy between apair made up of one of the first set of electromagnetic signalapplicators and one of the second set of electromagnetic signalapplicators other than the second electromagnetic signal applicator.106. The method according to aspect 105 wherein the second set ofelectromagnetic signal applicators comprises an array of electromagneticsignal applicators that includes a first ow of the electromagneticsignal applicators spaced apart along the patient's body adjacent to afirst one of the patient's lungs and a second column of theelectromagnetic signal applicators spaced apart along the patient's bodyadjacent to a second one of the patient's lungs.107. The method according to aspect 107 wherein the array ofelectromagnetic signal applicators comprises a plurality of columns ofthe electromagnetic signal applicators spaced apart along the patient'sbody adjacent to each one of the patient's lungs, each of the columnscomprising a plurality of the electromagnetic signal applicators.108. The method according to any of aspects 89 to 107 comprising whilethe one or more areas of diseased tissue within the lung is heated to atemperature at least equal to the treatment temperature thresholddeflating the patient's lung and subsequently reflating the patient'slung.109. The method according to any of aspects 89 to 108 wherein theelectromagnetic signal applicators comprise electrodes and applying theelectromagnetic energy to the tissues of the patient's lung comprisesdielectric heating of the lung tissues.110. The method according to aspect 109 comprising while applying theelectromagnetic energy moving a shield located between one of theelectrodes and the patient.111. The method according to aspect 110 wherein the shield has aspatially varying electrical impedance.112. The method according to any of aspects 89 to 108 wherein theelectromagnetic signal applicators comprise coils and applying theelectromagnetic energy to the tissues of the patient's lung comprisesinductively coupling the energy to the tissues.113. The method according to any one of aspects 89 to 112 wherein theelectromagnetic energy comprises radiofrequency energy.114. The method according to aspect 113 wherein the radiofrequencyenergy has a frequency of at least 1 MHz.115. The method according to aspect 113 wherein the radiofrequencyenergy has a frequency in the range of about 10 MHz to about 100 MHz.116. The method according to any one of aspects 89 to 115 comprisingapplying the electromagnetic energy to the entire lung of the patient.117. Apparatus having any new and inventive feature, combination offeatures, or sub-combination of features as described anywhere herein.118. Methods having any new and inventive steps, acts, combination ofsteps and/or acts or sub-combination of steps and/or acts as describedanywhere herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate non-limiting example embodiments ofthe invention.

FIG. 1 is a cross section of a patient's chest being exposed to anelectromagnetic field.

FIG. 2 is a view of the electrodes on the patient's back.

FIGS. 3A, 3B, 3C and 3D (collectively, FIG. 3) are cross sectional viewsof the patient's chest being exposed to an electromagnetic field,showing an alternative electrode arrangement.

FIG. 4 is a side view of the patient, showing a method of electrodeswitching.

FIGS. 5A and 5B (collectively, FIG. 5) are cross sectional views of apatient's chest showing the electrodes being supported by an inflatablevest. FIG. 5A illustrates a deflated vest. FIG. 5B shows an inflatedvest.

FIG. 6 is a cross section of a patient's chest being exposed to anelectromagnetic field being generated by coils.

FIGS. 7A and 7B (collectively, FIG. 7) are cross sectional views of apatient's chest showing a pair of electrodes being actuated to move in ahelical path around a patient's thorax as electromagnetic energy isbeing delivered.

FIG. 8 is a flow chart showing an exemplary method of treating unwantedtissues in a patient.

DETAILED DESCRIPTION

Throughout the following description, specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practiced without these particulars. Inother instances, well known elements have not been shown or described indetail to avoid unnecessarily obscuring the invention. Accordingly, thespecification and drawings are to be regarded in an illustrative, ratherthan a restrictive sense.

Methods and apparatus according to certain embodiments of the inventionmay be applied to selectively heat a diseased area of tissue in apatient while minimizing heating of other tissues in the patient.Heating may be achieved by exposing the diseased tissues to anelectromagnetic field to cause dielectric or eddy current heating. Theelectromagnetic field may comprise radiofrequency (RF) energy. In someembodiments the RF energy comprises microwave radiation.

By application of electromagnetic energy, selected diseased tissues maybe heated to temperatures above a threshold temperature. For example,diseased tissues may be heated to temperatures in the range of about 55degrees C. to about 65 degrees C. The exact temperature to whichdiseased tissues are heated is often not critical. In many cases,heating to a slightly lower maximum temperature can be compensated forby maintaining the temperature for a longer duration. It is desirable toavoid heating of healthy tissues because overheating healthy tissues candamage the healthy tissues. The maximum temperature to which healthytissue can be subjected without lasting damage is not known.

Certain embodiments of the invention are advantageously applied to treatdiseased tissues that have reduced blood flow as compared to nearbyhealthier tissues. In such cases the diseased area(s) may be heatedrapidly while the healthier tissues will be cooled by the blood flow andwill therefore experience reduced increase in temperature as compared tothe diseased tissues.

Emphysema is an example of a condition for which diseased area(s) havereduced blood flow. Certain embodiments of the invention can beparticularly effective for treating emphysema because of the low mass(density) of the lungs and the high blood flow in healthy tissues withinthe lungs.

In some cases the diseased tissues are tissues in the lungs of apatient. For example, the patient may suffer from emphysema. For suchtreatments electromagnetic energy may be applied to heat diseased areasto temperatures of about 50 degrees C. or more. While this is done thetemperatures of surrounding healthier lung tissue may be kept below athreshold temperature. The inventors estimate that healthy tissues inthe lungs and organs in the vicinity of the lungs should not besubjected to temperatures in excess of about 40 degrees C. or about 45degrees C.

FIG. 1 illustrates apparatus 10 according to an example embodiment ofthe invention being applied to treat diseased tissues within lungs 12and 14 of a patient P. Lungs 12 and 14 are surrounded by rib cage 16inside the patient's body 1. To heat diseased tissues within lungs 12and 14 while minimizing heat to adjacent organs like heart 18 and spine20, a plurality of electrodes 22 (FIG. 1 shows four electrodesindividually identified as 22A, 22B, 22C and 22D. In some embodimentsapparatus 10 includes additional electrodes 22. The additionalelectrodes 22 may, for example be located on one or both sides of theplane of the cross-section of FIG. 1.

Electrodes 22 are dimensioned and placed to create an electric field 24covering as much of lungs 12 and 14 as possible while minimizingpenetration of electric field 24 into adjacent organs. Fortunately, thehuman anatomy allows such a placement.

To improve electrical coupling of electromagnetic energy to body 1 whilecooling the surface of body 1, a saline solution 26 may optionally beintroduced by tubes 28 between body 1 and electrodes 22. Such a liquidcoupling can greatly improve the consistency of the coupling of the RFenergy delivered by way of some or all of electrodes 22 into body 1. Inalternative embodiments electrodes 22 comprise baths ofelectrically-conductive fluid such as, for example, saline solution.Saline solution 26 may, for example, comprise about 1 wt % NaCl inwater. In some other embodiments an electrically-conductive gel isprovided between electrodes 22 and body 1.

RF generator 30 supplies RF energy to electrodes 22 via an impedancematching network 32 and electrode selector circuit 34. The RF energy isapplied between two or more of electrodes 22 via wires 36.

In some example embodiments the RF generator 30 has a maximum poweroutput in the range of about 1 kW to about 5 kW. In some exampleembodiments, the RF energy output by RF generator 30 has a frequency orfrequencies in the range of about 1 MHz to about 100 MHz or about 10 MHzto about 100 MHz.

It is optional but generally desirable to choose frequencies forelectric field 24 in the industrial scientific and medical (ISM) bandsof the spectrum. Such frequency choices may reduce or avoid interferencebetween the RF energy generated by RF generator 30 and other signalssuch as communications signals. For example, RF generator 30 may have anoutput frequency of 13.56 MHz or 27 MHz.

Impedance matching network 32 is provided to match the output impedanceof RF generator 30 to the impedance of body 1. This facilitates theefficient delivery of energy into body 1. Impedance matching networksare well known in the art.

In an example embodiment impedance matching network 32 may comprise anLC circuit such as a capacitor connected in series between one outputterminal of RF generator 30 and electrode selector 38 followed by aninductor connected in parallel with electrode selector 38. The values ofthe capacitor and inductor may be determined after measuring theresistance and capacitance between pairs of electrodes 22 on body 1. Forexample, impedance matching network 34 may match a pure resistiveimpedance (e.g. 50 Ohms) of RF generator 30 to a complex impedance of ahuman or animal body.

Because the impedance presented by different patients may differ verysignificantly (e.g. the size of a patient can have a significant effecton the spacing of a pair of electrodes located on either side of apatient and whether or not a gel or conductive solution is provided cansignificantly affect impedance at the electrode-body interfaces) it canbe desirable to provide an adjustable impedance matching network. Theimpedance matching network may be adjustable to provide a best matchingof impedance for each of a plurality of electrode pairs.

In some embodiments the impedance matching network is self-adjusting(i.e. auto-tuning) to maximize delivery of power into the body.Technologies that can be used to auto-tune the matching network foroptimal power delivery (based for example on measurements of reflectedradiation) are described for example in: U.S. Pat. Nos. 5,364,392,9,028,482 and 9,192,422 as well as other publications known to those ofskill in the art.

To avoid resistive currents going through body 1, and for electricalsafety, it is desirable to provide capacitive coupling betweenelectrodes 22 and body 1. For example, one can coat electrodes 22 with avery thin layer of an insulating material. For example, a thin layer ofKapton™ tape may be applied between electrodes 22 and body 1.

Diseased tissues within one or both lungs 12, 14 may be heated byapplying the output of RF generator 30 between two of electrodes 22located on either side of the lung to be treated. Heating may becontinued for sufficient time to raise the diseased tissues totemperatures above a threshold temperature for a time sufficient toachieve a desired treatment outcome.

In order to minimize heating of adjacent organs the direction ofelectromagnetic field 24 may be changed periodically. This may beachieved by applying the output of RF generator 30 between differentpairs of electrodes 22. Different pairs of electrodes 22 may be selectedsuch that the electric field changes direction but always passes throughthe portion(s) of lungs 12, 14 containing the diseased tissue to betreated. When this is done, the diseased lung tissues will be heatedcontinuously while surrounding tissues will be heated onlyintermittently. In apparatus 10, electrode selector 38 switches theoutput of RF generator 30 to be applied between different pairs ofelectrodes 22. The switching frequency can be low. For example,electrode selector 38 may switch electrodes once every few seconds. Insome non-limiting examples, electrode selector 38 switches electrodes touse a different pair of electrodes deliver of heating energy once every30 to 300 seconds. In some non-limiting examples electrode selector 38switches electrodes to use a different pair of electrodes at a frequencyof 100 Hz or less.

In some cases the different pairs of electrodes 22 are selected suchthat a direction of alignment of the electric field within tissues ofthe patient is changed through an angle of at least 15 degrees (at least10 degrees, at least 20 degrees and at least 25 degrees are alsooptions) at least every few seconds (e.g. at least every 1 to 30seconds). In some cases the different pairs of electrodes 22 areselected such that the direction of alignment of the electric field doesnot remain in the same plane for more than a few seconds. This may befacilitated by providing a two dimensional array of electrodes 22adjacent each of the patient's lungs on at least one side of thepatient.

Pairs of electrodes may be selected such that a volume of tissue (e.g.lung tissue) that includes diseased areas to be treated lies betweenelectrodes of the selected pairs. By alternating applying heating energyusing different ones of the selected pairs of electrodes the diseasedareas within the volume of tissue may be heated consistently whilesurrounding tissues may be heated only some of the time. In someembodiments, for each lung, heating energy is delivered by way of oneselected pair of electrodes at a time. In some embodiments delivery ofheating energy is rotated among three or four or more selected pairs ofelectrodes. In such embodiments any one selected pair of electrodes maybe active approximately 1/N of the time where N is the number ofselected pairs of electrodes being used to apply heating energy to aparticular lung or other volume of tissue.

In some embodiments an array of electrodes that substantially covers anarea of a patient's lung is provided on a patient's chest and back. Theelectrode arrays may be mirror images of one another. Each of theelectrode arrays may be shaped to conform to a shape of the patient'slung. In some embodiments each of the arrays is two dimensional andcomprises plural columns each containing plural electrodes and pluralrows each containing plural electrodes. In some embodiments such arraysare provided for one of a patient's lungs. In some embodiments sucharrays are provided for both of a patient's lungs. Such arrays may beapplied as described herein to deliver heating energy to tissues ofeither or both of the patient's lungs.

The electrodes of a pair of electrodes may be energized with oppositepolarities. In some embodiments one electrode of a pair is grounded andthe other electrode is connected to an output of RF signal generator 30.In some embodiments one electrode of a pair is connected to one outputterminal of an RF signal generator and the other electrode is connectedto another output terminal of the RF signal generator 30.

Healthier tissues of lungs 12, 14 may be protected from being heated todamaging temperatures by the fact that healthy lung tissue has muchlarger blood circulation than diseased tissue. When a non-contact heatsource, such as radio-frequency (RF) energy, is directed at the lung theheat will be carried away from the healthy tissue by the blood flowwhile the diseased parts of the lung will heat up.

This works because the mass of the lungs is low (usually about 1 kg inan adult human) while blood flow through the lung is high (usually about5 kg/minute or about 5 liters per minute in an adult human). The bloodflow tends to equalize the temperature of healthy parts of the lung withthe rest of the body which effectively acts as a heat-sink having a massof tens of kilograms. This is 10 to 100 times larger than the effectiveheat sink mass for diseased portions of the lungs which is typicallyless than about one kilogram. When lungs are exposed to a form of energycausing heating, such as RF energy, the temperature rise of lung tissueswill be inversely proportional to the effective heat-sinking mass.Therefore, diseased tissues that have poor blood circulation will beheated to temperatures significantly higher than healthier tissues thathave normal blood circulation. Based on this, heating energy may beapplied to cause the diseased areas of lung tissue to be heated totemperatures in the range of 50-70 degrees C. while healthy lung areaswill only heat up a few degrees above normal body temperature.

To assist in keeping down the temperature of healthier parts of lungs12, 14, patient P may be breathing chilled air during the procedure. Thediseased parts of lungs 12, 14 will not get a sufficient amount ofchilled air to keep them cool. Cooling may also be facilitated by meansof an aerosol of liquefied air.

Methods as described herein may be implemented in ways that provide theadvantage that the location(s) of diseased area(s) does not need to beprecisely known in advance. Heating energy can be directed at the wholelung, but only the diseased areas will have their temperatures raisedsignificantly.

Treatment methods as described herein may be applied to achieve variousdesired outcomes. For example, in some cases a single treatment in whicha diseased tissue is heated to above a threshold temperature may besufficient to achieve a desired outcome. For example, the desiredoutcome may be a reduction of the volume of diseased tissue. A singletreatment may achieve sufficient volume reduction via fibrosis, ablationor other processes. In other cases the treatment may be repeated two ormore times over the course of hours, days, weeks or months to achieved adesired reduction of volume of diseased tissues or other desiredoutcome.

Some embodiments optionally exploit the fact that when diseased lungtissue is heated to a temperature in the vicinity of about 60 degrees C.the diseased lung tissue may lose the ability to expand back after lungsare collapsed (pneumothorax). This may result from temperature-induceddamage to the surfactant layer and other physiological reasons. Atreatment method may comprise heating diseased lung tissue (e.g. tissueaffected by COPD or emphysema) in a lung, collapsing the lung and thenre-inflating the lung.

Heating the lung may be performed quickly (e.g. in seconds or minutes).Collapsing the lung may be performed by inserting a hypodermic needleinto the pleural space and allowing air to leak into the pleural space.Supplying the lung with pure oxygen will speed up the collapse as itoxygen fully absorbed in the blood. The lung may be kept in a collapsedstate for long enough to allow the diseased area(s) to collapse into asmall volume. The lung may be re-inflated by evacuating the pleuralspace. This may be done, for example via the same needle used tocollapse the lung. The procedure can be done on one lung at a time. Thepatient can breathe with the remaining lung. Collapsing and inflatinglungs is done routinely in pulmonary medicine and need not be detailedhere.

This treatment may cause the areas affected by emphysema to collapse andstay collapsed so that these areas are prevented from interfering withnormal operation of the healthy parts of the lung. this may achieveresults similar to those that can be achieved by surgically removing thediseased lung tissues without the risks of surgery. Other mechanisms mayexist that do not require pneumothorax: the heated diseased area canlose volume through ablation, fibrosis or other mechanisms and allowhealthy lung tissue to fill the voids.

The heating process may be performed open-loop (i.e. based on a previousexperimental calibration of power and duration), or using sensing orclosed loop control. In some embodiments apparatus 10 includes acontroller that automatically controls one or more of: the power outputof RF generator 30, the electrodes between which the output of RFgenerator 30 is applied, a duty cycle of RF generator 30 and a durationof a period during which RF generator 30 applies heating energy to abody 1 based at least in part on real time measurements oftemperature(s) at one or more locations in tissues in a patient.

Temperature sensing may be performed using one or more sensors 36 placedin the patient's body and/or any suitable non-contact temperaturesensing technology. In an example embodiment temperature of tissueswithin a patient is sensed using small temperature sensors such asthermistors, For example, a prototype embodiment used miniature glassencased thermistors such as Digikey™ part number 495-5820-ND to measuretemperatures of lung tissues. Other example ways to measure temperaturesof tissues include:

-   -   hypodermic temperature sensors (these may for example comprise        an electronic temperature sensor carried in a very fine gage        needle (e.g. a needle about 0.6 mm in diameter);    -   processing data obtained by a magnetic resonance imaging (MRI)        system or other external imaging system capable of temperature        monitoring;    -   thermocouples;    -   a bronchoscope equipped with a thermistor or other temperature        sensor;    -   solid-state temperature sensors;    -   and the like.

A controller may implement any of various control algorithms. Forexample a controller of system 10 may implement a PID control loop. Acontroller may implement simple algorithms such as shutting off orreducing the power output of RF generator 30 when a desired temperaturehas been reached (e.g. a temperature in the range of about 55-65 degreesC.). In some embodiments the controller both modulates the power outputof RF generator 30 as the temperature of a tissue is raised toward adesired temperature and shuts of delivery of power by RF generator 30when the desired temperature has been reached. Feedback control canprevent the target temperature from being exceeded.

Embodiments that apply open-loop temperature control may optionallycalculate a current temperature within a tissue of interest based on amathematical model of the heat absorbed in the tissue and the coolingrate of the tissue. An output of the model may be applied to controlpower output of RF generator 30 and/or to stop RF generator 30 fromfurther raising temperature of tissues after the model predicts that athreshold temperature has been reached.

In some embodiments one or more temperature sensors are applied to sensetemperatures of non-targeted tissues. For example non-targeted organsidentified as being likely to heat up the most, or as being the organsmost sensitive to heat, may be identified and the temperatures withinthese organs may be monitored during treatment.

In an example embodiment a simple temperature sensor installed in ahypodermic needle provides accurate temperature measurements when theneedle is inserted into the organ. A controller for apparatus 10 may beconfigured to discontinue treatment if a temperature of a non-targetedtissue exceeds a safe temperature threshold and/or to modulateapplication of heating energy from RF generator 30 if the temperature ofthe non-targeted tissue is rising toward or close to the safetemperature threshold.

Non-target temperature sensors which sense temperature of non-targettissues may be used on their own or combined with temperature sensorsthat measure temperature of targeted tissues. In some embodiments thesame temperature sensor (e.g. an MRI-based temperature sensor or anothernon-contact temperature sensor) may monitor temperatures within bothtargeted tissues and non-targeted tissues.

Some embodiments modify the system described in U.S. Pat. No. 8,444,635to include a temperature sensor, a controller connected to receive atemperature signal from the temperature sensor and configured to controldelivery of radiation to heat tissues in a patient by a closed loopcontrol algorithm.

In some cases it can be undesirable to place a temperature sensor intarget tissues. For example, inserting a temperature sensor into certainareas of lung tissue could risk puncturing the lung. In some embodimentsa model of the patient's anatomy may be used to estimate how temperatureat a specific point in a targeted tissue and/or at a specific point in anon-targeted tissue relates to temperature at an alternative location inthe patient. The alternative location may be selected to be a locationat which a temperature sensor may be placed with lower risk and/orreduced adverse consequences. The other location may comprise one ormore of muscle surrounding the lungs, exhaled air temperature, bloodtemperature at a certain location or the like.

A thermal model of the patient's anatomy may be generated frompre-operative images. Known thermal conductivities of different tissuetypes may be combined with known distributions of those tissue types inthe patient, known geometries of electrodes, coils or other structuresto be used to deliver heating energy to the tissues and a circulationmodel to estimate how temperatures at the alternative location(s)correlate to temperatures at the locations of interest. Temperaturesmeasured at the alternative location(s) can then be used as proxies fortemperatures at the locations of interest using the correlationsdetermined using the model.

In some implementations the patient's orientation is taken intoconsideration. Lower parts of the lung typically contain more blood dueto the effect of gravity than parts of the lung at higher elevations.This is called ‘differential perfusion’. The parts of the lung thatcontain the most blood can vary with patient orientation. The amount ofblood at a location to be treated can affect the rate at which thetemperature of tissue at that location increases when electromagneticenergy is delivered to the tissue.

In some embodiments a patient is moved into different postures (e.g. byrotating and/or tilting the patient and or rolling the patient over) astreatment is delivered. Apparatus according to some embodiments of theinvention may provide a couch, chair, bed or other patient support thatmoves by tilting rotating or the like in coordination with the deliveryof treatments. In some embodiments motions of the patient support arecontrolled by a controller that also controls application of heatingenergy to the patient.

Apparatus according to some embodiments provides instructions (e.g. on adisplay) to change the posture of the patient at selected points duringa treatment.

Apparatus according to some embodiments estimates an effect ofdifferential perfusion on properties of tissues in different parts ofthe lung (or other part of the anatomy). Such estimates may be based forexample on information regarding the patient's anatomy (e.g. frompre-operative images). A profile for delivering energy to target tissuesmay take into account differential perfusion by increasing or decreasingthe delivered energy depending on whether the target tissues are in apart of the lung at which the target tissues are expected to experiencemore rapid temperature rise as a result of differential perfusion (e.g.energy may be decreased where the target tissue is at a higher elevationand so the target tissue is depleted of blood) or the target tissues areexpected to experience slower temperature rise as a result ofdifferential perfusion (e.g. energy may be increased where the targettissue is at a lower elevation and so the target tissue contains a largeamount of blood). Some embodiments of the apparatus provide a userinterface that includes a control that a user may use to indicate aposture of the patient during a treatment. Compensation for differentialperfusion may be based at least in part on the indicated posture.

It is generally desirable to apply electromagnetic energy to a patient'stissues such that the electric fields 24 within the tissues aregenerally uniform. Electric field 24 uniformity can be affected byvarious factors including:

-   -   The sizes, shapes and positions of the electrodes;    -   Impedance of the interface between the electrodes and the        patient's body;    -   The frequency or frequencies present in the electromagnetic        energy being delivered by way of the electrodes;    -   Where the electrodes are of different sizes, which electrode has        the highest voltages applied to it (tissues near high voltage        will tend to be heated to higher temperatures heat more quickly        because the rate of heating relates to density of field lines).        Some embodiments manipulate one or more of these factors to        achieve a desired electric field distribution in the patient.        For example:    -   electrodes may be constructed by choice of material and/or        coating to have a spatially-varying resistivity.    -   shields and/or waveguides may be interposed between the        electrodes and the body of the patient.    -   the electrodes (and/or shields and/or waveguides if present) may        be moved as treatments are delivered.        Features such as one or more of the above may be applied, for        example, to achieve a generally uniform distribution of electric        field in a lung or other volume of tissue to be treated.

In some embodiments an arrangement of electrodes 22 is designed orcustomized using knowledge of a patient's anatomy and the geometry ofthe target tissues. For example, MRI and/or computed tomography CTimages may be processed to identify regions of different consistency inthe patient (e.g. fat tissue/muscle/bone). Working from known averageelectrical properties of these materials one can design a treatment planthat specifies one or more of:

-   -   electrode arrangements;    -   electrode switching sequence and/or timing;    -   RF signal characteristics (power, frequency etc.);        The treatment plan may help to target the correct target        tissue(s), achieve sufficiently uniform heating, and avoid        excessive heating of critical tissue (heart, for example). In        some embodiments an electrode pattern that comprises arrays of        electrodes dimensioned to overlie a patient's lungs on two sides        (e.g. chest and back) of a patient's body is generated by        analysis of the patient's anatomy and a set of electrodes        customized for the patient is fabricated by printing, cutting or        other computer-controlled fabrication process using the        electrode pattern.

FIG. 2 shows an example arrangement of electrodes 22 on one side of apatient P (e.g. the patient's back) a similar arrangement of electrodesmay be provided on an opposing side of the patient (e.g. the patient'schest). In this and some other embodiments a separate set of electrodesis provided overlying each of the patient's lungs. Here, electrodes 22AAthrough 22AC are provided over the patient's left lung and electrodes22BA through 23BC are provided over the patient's right lung.

In this example, electromagnetic energy may be delivered to target lungtissues of the patient P by connecting the output of an RF generator 30between a pair of electrodes 22 which includes one electrode on thepatient's chest and another electrode on the patient's back. The pair ofelectrodes 22 may be directly opposed to one another in some cases andoffset from one another in others.

The electrode arrangement of FIG. 2 may be varied in different waysincluding, for example:

-   -   Replacing some or all of the illustrated electrodes with more        electrodes, which may be smaller than the depicted electrodes in        some cases.    -   Dividing the illustrated electrodes to provide more columns of        electrodes. The columns may, for example be arranged generally        parallel to the patient's spine on one or both sides of the        patient. For example, each of the illustrated electrodes 22 may        be replaced by a row of two or three electrodes. An exemplary        embodiment is shown in FIGS. 3A to 3D where each of the        electrodes 22A, 22B, 22C, and 22D has been replaced by two        electrodes.    -   Dividing the illustrated electrodes to include more rows of        electrodes.

An electrode selection circuit 34 as shown for example in FIG. 1 mayapply heating energy (e.g. an output from an RF signal generator) todifferent ones of the electrode pairs at different times (electrodeswitching).

FIG. 4 illustrates an example of electrode switching. FIG. 4 is a sideview of patient P in which electrodes 22AA through 22CC are shown.Electrodes 22CA through 22CC are on an opposite side of patient P fromelectrodes 22AA to 22AC. FIG. 4 shows that electrodes 22AA to 22CCprovide 9 pairs of electrodes 22 wherein the electrodes of each pairinclude one electrode on one side of patient P and another electrode onan opposing side of patient P such that patient P is sandwiched betweenthe electrodes of the pair.

The direction of an electric field 24 produced in patient P depends onwhich pair of electrodes 22 is being used to deliver heating energy. Forexample consider the three pairs of electrodes involving electrode 22CC.The electromagnetic field can be directed as shown by field lines 24, 25and 26 by respectively pairing electrode 22CC with electrodes 22AA, 22ABand 22AC.

FIG. 4 shows an example situation in which electrode selection circuit34 comprises electronically controlled switches or commutators 46 and48. The impedance matching network may be constructed to provide abalanced output (balanced relative to ground potential) where a balancedconfiguration is desired. In the illustrated embodiment this is achievedby providing transformer 50.

Switches 46 and 48 may comprise, for example, electro-mechanical relays,electro-mechanical commutators, solid state switches such as RF FETtransistors or RF relays or the like.

As shown in FIG. 4, different pairs of electrodes 22 may haveelectrode-to-electrode spacings that are significantly different. Someembodiments include mechanisms to compensate for different energydensities in body tissues that may result when heating energy isswitched among different electrode pairs. Such compensation may, forexample, take one or more of the following forms:

-   -   A controller may automatically set power output of RF generator        30 to different values depending on which pair of electrodes is        being driven.    -   Some electrodes may be split into plural sections. Different        ones of the sections or different combinations of the sections        may be used depending on which other electrode the electrode is        paired with.    -   Pulse width modulation or other time domain compensation may be        applied depending on which pair of electrodes 22 is being        driven.    -   A larger number of electrodes 22 may be provided such that more        different pairs of electrodes 22 that produce similar energy        densities when driven are available for selection.    -   An impedance matching network may be tuned or switched to match        the impedance presented by different pairs of electrodes.    -   combinations of any two or more of the above.    -   etc.

Electrodes 22 for use in applying heating energy to a patient may haveany of a wide variety of forms including stick-on electrodes, electrodesmounted on a belt or the like, electrodes 22 supported by clothing suchas a vest or the like. An exemplary vest 58 is shown in FIG. 5. Vest 58may be inflatable. FIG. 5A shows vest 58 prior to inflation. FIG. 5Bshows vest 58 that is inflated. In some embodiments some or allelectrodes 22 comprise bladders containing an electrically-conductiveliquid. Such electrodes can be advantageous where apparatus as describedherein incorporates or is used in conjunction with a MRI system. Duringtimes when it is desired to deliver energy to the patients' tissues thebladders may be filled with the electrically-conductive fluid. Duringtimes when it is desired to obtain MRI information theelectrically-conductive fluid may be withdrawn from the bladders.

Ideally the electrodes are provided in a way that simplifies applyingthe electrodes to the bodies of patients such that the electrodes are inclose contact with the patients' bodies.

In some embodiments, some or all of electrodes 22 have one or more ofthe following features:

-   -   the electrodes are stretchable in length and/or width (for        example, the electrodes may be made from an        electrically-conductive stretchable fabric or a woven or        non-woven conductive mesh or a sheet of a stretchable conductive        plastic);    -   the electrodes are bendable;    -   the electrodes are attached to or are attachable to a vest, belt        or other clothing article (for example using an adhesive or a        hook and loop fabric coupling, or a clip, removable fastener, or        the like);    -   the electrodes are designed to be made smaller, for example by        cutting or tearing off to a size suitable for a particular        patient;    -   the electrodes are made up of plural smaller electrodes,        optionally connections between the smaller electrodes can be        made or broken to adjust the sizes of the electrodes to suit        individual patients.

Electrodes 22 may be held in place on a patient P, for example, by oneor more of:

-   -   an adhesive (which may comprise a self-adhesive and/or a        separately-applied adhesive) and/or gel;    -   an article of clothing to which the electrodes are attached or        integrated into;    -   an article of clothing such as, for example, a stretchy and/or        inflatable vest or shirt worn over top of the electrodes;    -   etc.

Where it is desirable to hold an electrode 22 against a part of apatient's body 1 that may be concave in form (e.g. the spine, areasaround breasts etc.) a formed member such as a bendable support orinflatable chamber (which may be part of an inflatable article ofclothing such as a vest) or the like may be provided to hold theelectrode against the concave part of the patient's anatomy.

Where some or all electrodes 22 are provided on a support such as anarticle of clothing (e.g. a vest) or patient furniture such as atreatment couch, bed table or chair, the support may include passages inwhich a cool fluid is contained and/or circulating. The cool fluid mayhelp to keep the patient cool. If the support is inflatable the passagescontaining the cool fluid may be the same as or different from chambersthat can be pressurized to inflate the support. In some embodimentsvalves are provided such that circulation of the cool fluid may beinhibited in parts of the support that are in close proximity to atarget tissue.

As described below, some embodiments provide coils instead of or inaddition to electrodes. In such embodiments the coils may be supportedagainst a patient in the same or similar ways as described above forelectrodes. This is best illustrated in FIG. 6.

The innovations described herein may be applied in contexts which applyheating energy to body tissues in different ways. For example,electromagnetic energy can be coupled into a body to heat tissues by:

-   -   Placing at least one pair of electrodes on either side of the        body such that at least a portion of the body is between the        electrodes (effectively forming a capacitor in which the tissues        of the body forms a dielectric) and deliver RF energy across the        electrodes. Dielectric losses within the tissue will generate        heat.    -   Place at least a part of the body inside a coil or sandwiched        between several coils to form an inductor, drive a RF signal        across the inductor and use the losses of this inductor (mainly        eddy current losses) to generate heat in tissues of the body.        Eddy current heating results where eddy currents in the        patient's tissues are induced by a changing magnetic field.    -   Radiate electromagnetic energy into the body from an antenna, as        disclosed for example in U.S. Pat. No. 8,444,635. Heating by        radiating electromagnetic radiation into the body is mainly        suitable for high frequencies such as microwave frequencies.        Closed-loop temperature control as described herein and/or        switching the direction of electromagnetic field lines to reduce        heating of non-targeted tissues may be provided in embodiments        which apply any of these heating methods.

In order to control which areas are heated when using lower RFfrequencies (e.g. 1 MHz to 100 MHz) the electrodes or coils that applythe RF energy to the body should be placed on opposing sides of thebody. Placing electrodes or coils just on one side of the body willcreate uneven heating, with most heat generated near the electrodes orcoils.

Various example embodiments are described herein in whichelectromagnetic energy is applied to a lung or other structure by way ofelectrodes. Other corresponding embodiments may be provided by replacingthe electrodes with coils.

For eddy current and mainly magnetic field induced heating, electrodescan be replaced by RF coils, as shown in FIG. 6. The polarity of coils52 and 54 is selected to create magnetic field lines 56 going throughthe lungs 12, 14. Multiple coils can be used in a coil switchingarrangement similar to the electrode switching arrangements disclosedelsewhere herein. The magnetic field can be further directed by usingferrite blocks.

Instead of providing fixed electrodes or coils apparatus may provideelectrodes or coils that are movable relative to a patient P. Forexample: One or more pairs of electrodes may be carried on an actuatoroperative to move the pairs of electrodes relative to a patient. Thepairs of electrodes may each include first and second electrodes thatare respectively movable over first and second faces of the patient(e.g. chest and back of the patient). For example, one pair ofelectrodes 22 may be actuated to move in a helical path around apatient's thorax as electromagnetic energy is delivered by way of theelectrodes 22, as shown in FIGS. 7A and 7B. As another example, one ormore pairs of electrodes may be fixed in at least one dimension and thepatient may be moved in the dimension relative to the fixed electrodes.

Apparatus according to some embodiments includes or is used inconjunction with a Faraday cage or shielded room to reduceelectromagnetic interference with other equipment. In some embodiment,shielding is provided by a wire mesh cage made up of wires spaced apartby a few centimeters or less. The cage may be integrated into walls orother structures of a room.

EXAMPLE

A method as described herein was tested on rats. It was found out thatminiature thermistors work well as direct temperature sensors while thethermocouples tested did not perform well. It is believed that theelectric field interfered with the low level (under one mV), signalsfrom thermocouples but not with the higher level (volts) signal from thethermistors. By the way of example, a suitable thermistor is model H1744made by the U.S. Pat. No. Sensor company (http://www.ussensor.com/).This thermistor has an outside diameter of 0.43 mm.

The system was tested on several rats with induced emphysema in one ofthe lungs. The parameters used were:

-   -   RF power of 100 W at 13.56 MHz.    -   Series C parallel L matching network with saline irrigated        electrodes.

Reflected power was under 5%. Each electrode was approximately 25×50 mm,coated with 25 μm thick Kapton™ tape. The tape does not attenuate thecapacitive currents much because it is very thin, therefore allowinghigh capacitance between electrode and the body. Rats were shaved in theareas of contact with the electrodes.

Heating time was about 100 seconds. The healthy lung reached about 41degrees C., while the areas with emphysema reached about 55 degrees C.All rats survived the treatment. Subsequent autopsy verified scar tissuein the areas of induced emphysema.

In the tests conducted on rats the dielectric heating was more effectivethan the magnetic field induced heating, but there may be uniquebenefits to each one of them.

Interpretation of Terms

Unless the context clearly requires otherwise, throughout thedescription and the claims:

-   -   “comprise”, “comprising”, and the like are to be construed in an        inclusive sense, as opposed to an exclusive or exhaustive sense;        that is to say, in the sense of “including, but not limited to”;    -   “connected”, “coupled”, or any variant thereof, means any        connection or coupling, either direct or indirect, between two        or more elements; the coupling or connection between the        elements can be physical, logical, or a combination thereof;    -   “herein”, “above”, “below”, and words of similar import, when        used to describe this specification, shall refer to this        specification as a whole, and not to any particular portions of        this specification;    -   “or”, in reference to a list of two or more items, covers all of        the following interpretations of the word: any of the items in        the list, all of the items in the list, and any combination of        the items in the list;    -   the singular forms “a”, “an”, and “the” also include the meaning        of any appropriate plural forms.    -   “electromagnetic signal applicator” is a generic term that        encompasses electrodes (e.g. which may be used to apply electric        fields for dielectric heating), coils, (e.g. which may be used        to apply magnetic fields for eddy current heating, and antennas        (e.g. which may be used to apply microwaves to heat tissues).

Words that indicate directions such as “vertical”, “transverse”,“horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”,“outward”, “vertical”, “transverse”, “left”, “right”, “front”, “back”,“top”, “bottom”, “below”, “above”, “under”, and the like, used in thisdescription and any accompanying claims (where present), depend on thespecific orientation of the apparatus described and illustrated. Thesubject matter described herein may assume various alternativeorientations. Accordingly, these directional terms are not strictlydefined and should not be interpreted narrowly.

Certain embodiments of the invention incorporate control systems orcontrollers. Such controllers or control systems may be implementedusing specifically designed hardware, configurable hardware,programmable data processors configured by the provision of software(which may optionally comprise “firmware”) capable of executing on thedata processors, special purpose computers or data processors that arespecifically programmed, configured, or constructed to perform one ormore steps in a method as explained in detail herein and/or combinationsof two or more of these. Examples of specifically designed hardware are:logic circuits, application-specific integrated circuits (“ASICs”),large scale integrated circuits (“LSIs”), very large scale integratedcircuits (“VLSIs”), and the like. Examples of configurable hardware are:one or more programmable logic devices such as programmable array logic(“PALs”), programmable logic arrays (“PLAs”), and field programmablegate arrays (“FPGAs”)). Examples of programmable data processors are:microprocessors, digital signal processors (“DSPs”), embeddedprocessors, graphics processors, math co-processors, general purposecomputers, server computers, cloud computers, mainframe computers,computer workstations, and the like. For example, one or more dataprocessors in a control circuit for a device may implement methods asdescribed herein by executing software instructions in a program memoryaccessible to the processors.

For example, while processes or blocks are presented in a given order,alternative examples may perform routines having steps, or employsystems having blocks, in a different order, and some processes orblocks may be deleted, moved, added, subdivided, combined, and/ormodified to provide alternative or subcombinations. Each of theseprocesses or blocks may be implemented in a variety of different ways.Also, while processes or blocks are at times shown as being performed inseries, these processes or blocks may instead be performed in parallel,or may be performed at different times.

Software and other modules may reside on servers, workstations, personalcomputers, tablet computers, embedded controllers, process controllersand other devices suitable for the purposes described herein.

The invention may also be provided in the form of a program product. Theprogram product may comprise any non-transitory medium which carries aset of computer-readable instructions which, when executed by a dataprocessor, cause the data processor to execute a method of theinvention. Program products according to the invention may be in any ofa wide variety of forms. The program product may comprise, for example,non-transitory media such as magnetic data storage media includingfloppy diskettes, hard disk drives, optical data storage media includingCD ROMs, DVDs, electronic data storage media including ROMs, flash RAM,EPROMs, hardwired or preprogrammed chips (e.g., EEPROM semiconductorchips), nanotechnology memory, or the like. The computer-readablesignals on the program product may optionally be compressed orencrypted.

In some embodiments, the invention may be implemented in software. Forgreater clarity, “software” includes any instructions executed on aprocessor, and may include (but is not limited to) firmware, residentsoftware, microcode, and the like. Both processing hardware and softwaremay be centralized or distributed (or a combination thereof), in wholeor in part, as known to those skilled in the art. For example, softwareand other modules may be accessible via local memory, via a network, viaa browser or other application in a distributed computing context, orvia other means suitable for the purposes described above.

Where a component (e.g. an electrode, oscillator, switch, controller,temperature sensor, software module, processor, assembly, device,circuit, etc.) is referred to above, unless otherwise indicated,reference to that component (including a reference to a “means”) shouldbe interpreted as including as equivalents of that component anycomponent which performs the function of the described component (i.e.,that is functionally equivalent), including components which are notstructurally equivalent to the disclosed structure which performs thefunction in the illustrated exemplary embodiments of the invention.

Specific examples of systems, methods and apparatus have been describedherein for purposes of illustration. These are only examples. Thetechnology provided herein can be applied to systems other than theexample systems described above. Many alterations, modifications,additions, omissions, and permutations are possible within the practiceof this invention. This invention includes variations on describedembodiments that would be apparent to the skilled addressee, includingvariations obtained by: replacing features, elements and/or acts withequivalent features, elements and/or acts; mixing and matching offeatures, elements and/or acts from different embodiments; combiningfeatures, elements and/or acts from embodiments as described herein withfeatures, elements and/or acts of other technology; and/or omittingcombining features, elements and/or acts from described embodiments.

Methods according to the examples described herein may be varied. Forexample, while elements are at times shown as being performedsequentially, they may instead be performed simultaneously or indifferent sequences.

It is therefore intended that the following appended claims and claimshereafter introduced are interpreted to include all such modifications,permutations, additions, omissions, and sub-combinations as mayreasonably be inferred. The scope of the claims should not be limited bythe preferred embodiments set forth in the examples, but should be giventhe broadest interpretation consistent with the description as a whole.

What is claimed is:
 1. Medical thermal ablation apparatus useful fortreatment of emphysema or COPD, the apparatus comprising: a plurality ofelectromagnetic signal applicators, the plurality of electromagneticsignal applicators adapted to deliver electromagnetic energy to lungtissues for differential heating of diseased and healthier portions ofthe lung tissues, the plurality of electromagnetic signal applicatorscomprising a first set of two or more first electromagnetic signalapplicators positionable on one side of a body to be treated and asecond set of at least one second electromagnetic signal applicatorspositionable on a second side of the body to be treated opposed to thefirst side such that the body is between the first and secondelectromagnetic signal applicators; a heating energy signal generator;and a selector circuit connected to receive an output signal from theheating energy signal generator and operative to selectively apply theoutput signal between a selected one or more of the firstelectromagnetic signal applicators and a selected one or more of thesecond electromagnetic signal applicators and to switch from applyingthe output signal between the currently selected first and secondelectromagnetic signal applicators to between a different selectedcombination of one or more of the first electromagnetic signalapplicators and one or more of the second electromagnetic signalapplicators at spaced apart times; wherein at least one of the first andsecond electromagnetic signal applicators is stationary and theapparatus comprises a controller and an actuator controlled by thecontroller and operable to move the body relative to the at least one ofthe first and second electromagnetic signal applicators.
 2. The medicalthermal ablation apparatus according to claim 1 wherein theelectromagnetic signal applicators each comprises an electrode.
 3. Themedical thermal ablation apparatus according to claim 2 comprising animpedance matching network between the heating energy signal generatorand the electrodes and the controller wherein the impedance matchingnetwork comprises a plurality of settings, each of the settings providesimpedance matching for at least one of a plurality of pairs of theelectrodes, each of the pairs of electrodes correspond to one of thesettings and the controller is connected to control the impedancematching network to switch the impedance matching network to the settingcorresponding to a currently selected one of the pairs of electrodes. 4.The medical thermal ablation apparatus according to claim 2 wherein theapparatus comprises a source of a fluid connected to supply the fluid tooutlets at the electrodes.
 5. The medical thermal ablation apparatusaccording to claim 2 wherein at least some of the electrodes comprisebladders connected to a supply of a fluid and the apparatus comprisesone or more pumps connected to evacuate the fluid and the controller isconfigured to operate the one or more pumps to evacuate the fluid fromone or more of the bladders, when the fluid has been evacuated from theone or more bladders operate a MRI machine to acquire MRI data from thebody.
 6. The medical thermal ablation apparatus according to claim 1wherein the heat energy signal generator has first and second outputsand one of the first and second outputs of the heat energy signalgenerator is grounded and the selector circuit is configured toselectively connect the first output to the selected one or more of thefirst electromagnetic signal applicators and to selectively connect thesecond output to the a selected one or more of the secondelectromagnetic signal applicators.
 7. The medical thermal ablationapparatus according to claim 1 wherein the heating energy signalgenerator comprises a radiofrequency (RF) signal generator.
 8. Themedical thermal ablation apparatus according to claim 7 wherein the RFsignal generator is operable to output a signal having a frequency in anISM band in the range of about 1 MHz to about 100 MHz.
 9. The medicalthermal ablation apparatus according to claim 1 wherein the controlleris connected to receive a signal indicative of a temperature of tissueat one or more locations within the body and configured to applyfeedback control to regulate heating energy delivered into the body fromthe heat energy signal generator based at least in part on thetemperature signal.
 10. The medical thermal ablation apparatus accordingto claim 9 further comprising a subcutaneous and/or invasive temperaturesensor wherein the temperature signal comprises an output signal fromthe subcutaneous and/or invasive temperature sensor.
 11. The medicalthermal ablation apparatus according to claim 9 wherein the controllercomprises a thermal model of at least a portion of the body, the thermalmodel correlating temperature at one of the locations to temperature ofa location of interest and the controller is configured to apply thethermal model using the temperature signal as an input and to regulatethe heating energy based at least in part on an output of the thermalmodel.
 12. The medical thermal ablation apparatus according to claim 9wherein the temperature signal is derived from an external systemcapable of temperature monitoring.
 13. The medical thermal ablationapparatus according to claim 9 wherein the temperature signal comprisesa signal derived from processing a magnetic resonance imaging (MRI)signal.
 14. The medical thermal ablation apparatus according to claim 9wherein the controller is configured to regulate the heating energy toraise a temperature at one of the one or more locations to a temperatureof at least 50 C and to maintain the temperature at 50 C or higher for aselected time period.
 15. The medical thermal ablation apparatusaccording to claim 9 wherein the controller is configured to regulatethe heating energy to prevent the temperature at one of the one or morelocations from exceeding a safe temperature threshold.
 16. The medicalthermal ablation apparatus according to claim 1 wherein the controlleris configured to perform one or more of: controlling a power of theoutput signal; applying time domain modulation to the output signal; andcontrolling the heat energy signal generator to emit the output signalas a pulsed signal wherein the controller is configured to controlwidths of the pulses.
 17. The medical thermal ablation apparatusaccording to claim 2 wherein the electrodes of at least one of the firstand second sets of electromagnetic signal applicators are arranged in atwo-dimensional array.
 18. The medical thermal ablation apparatusaccording to claim 1 wherein the first and second sets ofelectromagnetic signal applicators respectively comprise first andsecond two-dimensional arrays of electrodes wherein each electrode ofthe first array of electrodes is positioned opposite a correspondingelectrode of the second array of electrodes.
 19. The medical thermalablation apparatus according to claim 1 wherein the electromagneticsignal applicators each comprises a coil.
 20. Medical thermal ablationapparatus useful for treatment of emphysema or COPD, the apparatuscomprising: a plurality of electromagnetic signal applicators, theplurality of electromagnetic signal applicators adapted to deliverelectromagnetic energy to lung tissues for differential heating ofdiseased and healthier portions of the lung tissues, the plurality ofelectromagnetic signal applicators comprising a first set of two or morefirst electromagnetic signal applicators positionable on one side of abody to be treated and a second set of at least one secondelectromagnetic signal applicators positionable on a second side of thebody to be treated opposed to the first side such that the body isbetween the first and second electromagnetic signal applicators; aheating energy signal generator; a selector circuit connected to receivean output signal from the heating energy signal generator and operativeto selectively apply the output signal between a selected one or more ofthe first electromagnetic signal applicators and a selected one or moreof the second electromagnetic signal applicators and to switch fromapplying the output signal between the currently selected first andsecond electromagnetic signal applicators to between a differentselected combination of one or more of the first electromagnetic signalapplicators and one or more of the second electromagnetic signalapplicators at spaced apart times; and bias means for biasing one ormore of the electromagnetic signal applicators toward the body wherein:the bias means comprises an inflatable chamber and a source of apressurized cool fluid in fluid communication with the inflatablechamber; and the one or more of the electromagnetic signal applicatorsis flexible and the bias means is adapted to flex the one or more of theelectromagnetic signal applicators to conform to a concave surface.